The closest prior art is the disclosure of U.S. Pat. No. 4,014,635, which issued Mar. 29, 1977, to Karl Kristian Kobs Kroyer for an "Apparatus for the Deposition of a Uniform Layer of Dried Fibers on a Foraminous Forming Surface".
The Kroyer apparatus comprises a distributor including a housing which is substantially rectangular, having curved side wall sections. One or more propeller-like impellers are within the distributor housing and spin about one or more vertical shafts. Fibrous material such as paper pulp is introduced above the impellers. Optionally, a screen may be used ahead of the impellers initially to screen particularly large fibers. A vacuum port is connected to the housing to remove extra large fibers and to return them to a hammer mill where they may be reduced to smaller fibers and returned to the distributor. The distributor housing has an opening at its lower end, below the impellers, and a screen extends over the opening to prevent passage therethrough of fibers larger than a predetermined size. Below that screen is a forming wire for receiving fibers that pass through the screen. Movement of the forming wire spreads the fibers into a continuous web. The region below the forming wire is partly evacuated to induce air flow downwardly from the distributor through the screen over the distributor opening, and through the forming wire, thereby holding the formed fibrous web on the forming wire. The forming wire preferably is in a tunnel, and the tunnel is substantially sealed at both ends by a pair of rollers.
Unfortunately, the motion of the forming wire tends to cause the fibers to align or orient in the direction of travel, thereby forming a web which is stronger in one direction than in another. It is desirable that the fibers be randomly oriented to give a substantially isotropic strength to the fibrous web.